U.S. patent number 10,077,367 [Application Number 15/128,266] was granted by the patent office on 2018-09-18 for coated metal plate and exterior building material.
This patent grant is currently assigned to NISSHIN STEEL CO., LTD.. The grantee listed for this patent is NISSHIN STEEL CO., LTD.. Invention is credited to Taketo Hara, Kenji Sakato, Kazuhiko Takahashi, Hirokazu Yano.
United States Patent |
10,077,367 |
Hara , et al. |
September 18, 2018 |
Coated metal plate and exterior building material
Abstract
This coated metal plate is a chromate-free coated metal plate
for exterior applications, which comprises a metal plate and a
coating film that is arranged on the metal plate. The coating film
contains 0.2-15 vol % of porous particles as a gloss control agent,
and contains 0.2-15 vol % of primary particles as a matting agent.
If R1 (.mu.m) is the number average particle diameter of the gloss
control agent, R2 (.mu.m) is the number average particle diameter
of the matting agent, T (.mu.m) is the film thickness of the
coating film, .sigma.1 (.mu.m) is the standard deviation of the
number-based particle size distribution of the gloss control agent
and .sigma.2 (.mu.m) is the standard deviation of the number-based
particle size distribution of the matting agent, the coated metal
plate satisfies the following formulae. (R1+2.sigma.1)/T.ltoreq.0.7
R1.gtoreq.2.0 2.0.ltoreq.(R2+2.sigma.2)/T.ltoreq.7.0
13.ltoreq.T.ltoreq.20.
Inventors: |
Hara; Taketo (Chiba,
JP), Yano; Hirokazu (Chiba, JP), Sakato;
Kenji (Chiba, JP), Takahashi; Kazuhiko (Chiba,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
NISSHIN STEEL CO., LTD. |
Tokyo |
N/A |
JP |
|
|
Assignee: |
NISSHIN STEEL CO., LTD. (Tokyo,
JP)
|
Family
ID: |
51427305 |
Appl.
No.: |
15/128,266 |
Filed: |
March 26, 2014 |
PCT
Filed: |
March 26, 2014 |
PCT No.: |
PCT/JP2014/001744 |
371(c)(1),(2),(4) Date: |
September 22, 2016 |
PCT
Pub. No.: |
WO2015/145482 |
PCT
Pub. Date: |
October 01, 2015 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
|
US 20170101545 A1 |
Apr 13, 2017 |
|
Foreign Application Priority Data
|
|
|
|
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Mar 24, 2014 [JP] |
|
|
2014-059950 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09D
5/08 (20130101); B32B 5/18 (20130101); C09D
5/082 (20130101); B32B 15/18 (20130101); C23C
26/00 (20130101); B05D 7/53 (20130101); C09D
7/69 (20180101); B05D 7/16 (20130101); B05D
5/02 (20130101); C09D 7/61 (20180101); B05D
7/54 (20130101); C09D 7/42 (20180101); B32B
15/20 (20130101); C23C 22/34 (20130101); B32B
2307/714 (20130101); B05D 2350/65 (20130101); B32B
2419/00 (20130101) |
Current International
Class: |
B21D
39/00 (20060101); C09D 7/00 (20180101); C23C
26/00 (20060101); C09D 7/42 (20180101); C09D
7/61 (20180101) |
Field of
Search: |
;428/623 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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5-228433 |
|
Sep 1993 |
|
JP |
|
10-128905 |
|
May 1998 |
|
JP |
|
2002-178447 |
|
Jun 2002 |
|
JP |
|
2004-154993 |
|
Jun 2004 |
|
JP |
|
2004-244720 |
|
Sep 2004 |
|
JP |
|
2004-269921 |
|
Sep 2004 |
|
JP |
|
2009-233498 |
|
Oct 2009 |
|
JP |
|
2011-148107 |
|
Aug 2011 |
|
JP |
|
2011-207208 |
|
Oct 2011 |
|
JP |
|
2012-082944 |
|
Apr 2012 |
|
JP |
|
2012-214010 |
|
Nov 2012 |
|
JP |
|
2012-214676 |
|
Nov 2012 |
|
JP |
|
5568191 |
|
Aug 2014 |
|
JP |
|
2010/071150 |
|
Jun 2010 |
|
WO |
|
Other References
TAFTIC(TM) ASF series [online], Toyobo AP department, Apr. 9, 2014
(searching date), Product introduction: Polyacrylonitrite type
particles, Excellent matting agent TAFTIC ASF series
<URL;http://toyobo.co.jp/seihin/ap/taftic/pan/asf.html>.
cited by applicant .
International Search Report from International Application No.
PCT/JP2014/001744 dated Jul. 1, 2014. cited by applicant.
|
Primary Examiner: Sample; David
Assistant Examiner: Omori; Mary I
Attorney, Agent or Firm: Brundidge & Stanger, P.C.
Claims
The invention claimed is:
1. A coated metal sheet being chromate-free and comprising a metal
sheet and an overcoat coating film disposed on the metal sheet,
wherein the metal sheet is any one selected from the group
consisting of a cold-rolled steel sheet, a galvanized steel sheet,
a Zn--Al alloy-plated steel sheet, a Zn--Al--Mg alloy-plated steel
sheet, an aluminum-plated steel sheet, a stainless steel sheet, and
a copper sheet, wherein the overcoat coating film comprises a gloss
adjusting agent which is particles having micropores and a matting
agent which is primary particles, wherein a content of the gloss
adjusting agent in the overcoat coating film is 0.2 to 15 vol %,
wherein a content of the matting agent in the overcoat coating film
is 0.2 to 15 vol %, and wherein the coated metal sheet satisfies
the following equations: (R1+2.sigma.1)/T.ltoreq.0.7 R1.gtoreq.2.0
2.0.ltoreq.(R2+2.sigma.2)/T.ltoreq.7.0 13.ltoreq.T.ltoreq.20
.sigma.1<0.3T wherein R1 (.mu.m) is a number average particle
diameter of the gloss adjusting agent, R2 (.mu.m) is a number
average particle diameter of the matting agent, T (.mu.m) is a film
thickness of the overcoat coating film, .sigma.1 is a standard
deviation of a number particle size distribution of the gloss
adjusting agent, and .sigma.2 is a standard deviation of a number
particle size distribution of the matting agent.
2. The coated metal sheet according to claim 1, further comprising
an undercoat coating film between the metal sheet and the overcoat
coating film.
3. The coated metal sheet according to claim 1, wherein the gloss
adjusting agent is silica.
4. The coated metal sheet according to claim 1, wherein a value L
of the overcoat coating film is 80 or less, and the film thickness
T of the overcoat coating film is 15 .mu.m or less.
5. The coated metal sheet according to claim 1, wherein a value L
of the overcoat coating film is more than 80, and the film
thickness T of the overcoat coating film is more than 15 .mu.m.
6. The coated metal sheet according to claim 1, wherein an absolute
value .DELTA.L of a difference between a value L of the overcoat
coating film and a value L of a color of a surface of the metal
sheet before the overcoat coating film is formed is 10 or less, and
the film thickness T of the overcoat coating film is 13 .mu.m or
less.
7. The coated metal sheet according to claim 1, wherein an absolute
value .DELTA.L of a difference between a value L of the overcoat
coating film and a value L of a color of a surface of the metal
sheet before the overcoat coating film is formed is 20 or less, and
the film thickness T of the overcoat coating film is 15 .mu.m or
less.
8. The coated metal sheet according to claim 1, wherein an absolute
value .DELTA.L of a difference between a value L of the overcoat
coating film and a value L of a color of a surface of the metal
sheet before the overcoat coating film is formed is 50 or less, and
the film thickness T of the overcoat coating film is 17 .mu.m or
less.
9. The coated metal sheet according to claim 1, wherein the coated
metal sheet has a glossiness at 75 degrees of 1 to 25.
10. The coated metal sheet according to claim 1, wherein the coated
metal sheet is a coated metal sheet for exterior use.
11. An exterior building material composed of the coated metal
sheet according to claim 1.
12. The exterior building material according to claim 11, further
comprising one or more selected from the group consisting of
members to fix the exterior building material to a building,
members to connect a plurality of the exterior building materials,
marks that show a direction of the exterior building material on
mounting, and foam sheets or foam layers to improve thermal
insulation properties.
13. A coated metal sheet being chromate-free and comprising a metal
sheet and an overcoat coating film to be disposed on the metal
sheet, wherein the metal sheet is any one selected from the group
consisting of a cold-rolled steel sheet, a galvanized steel sheet,
a Zn--Al alloy-plated steel sheet, a Zn--Al--Mg alloy-plated steel
sheet, an aluminum-plated steel sheet, a stainless steel sheet, and
a copper sheet, wherein the overcoat coating film comprises a gloss
adjusting agent which is particles having micropores and a matting
agent which is primary particles, wherein a content of the gloss
adjusting agent in the overcoat coating film is 0.2 to 15 vol %,
wherein a content of the matting agent in the overcoat coating film
is 0.2 to 15 vol %, and wherein the coated metal sheet satisfies
the following equations: R1.gtoreq.2.0
2.0.ltoreq.(R2+2.sigma.2)/T.ltoreq.7.0 13.ltoreq.T.ltoreq.20
wherein R1 (.mu.m) is a number average particle diameter of the
gloss adjusting agent, R2 (.mu.m) is a number average particle
diameter of the matting agent, T (.mu.m) is a film thickness of the
overcoat coating film, and .sigma.2 is a standard deviation of a
number particle size distribution of the matting agent, and a
maximum value of a particle diameter in a number particle size
distribution of the gloss adjusting agent is 0.7T or less.
14. The coated metal sheet according to claim 13, wherein the
maximum value of the particle diameter in the number particle size
distribution of the gloss adjusting agent is 0.6T or less.
15. The coated metal sheet according to claim 13, further
comprising an undercoat coating film between the metal sheet and
the overcoat coating film.
16. The coated metal sheet according to claim 13, wherein the gloss
adjusting agent is silica.
17. The coated metal sheet according to claim 13, wherein a value L
of the overcoat coating film is 80 or less, and the film thickness
T of the overcoat coating film is 15 .mu.m or less.
18. The coated metal sheet according to claim 13, wherein a value L
of the overcoat coating film is more than 80, and the film
thickness T of the overcoat coating film is more than 15 .mu.m.
19. The coated metal sheet according to claim 13, wherein an
absolute value .DELTA.L of a difference between a value L of the
overcoat coating film and a value L of a color of a surface of the
metal sheet before the overcoat coating film is formed is 10 or
less, and the film thickness T of the overcoat coating film is 13
.mu.m or less.
20. The coated metal sheet according to claim 13, wherein an
absolute value .DELTA.L of a difference between a value L of the
overcoat coating film and a value L of a color of a surface of the
metal sheet before the overcoat coating film is formed is 20 or
less, and the film thickness T of the overcoat coating film is 15
.mu.m or less.
21. The coated metal sheet according to claim 13, wherein an
absolute value .DELTA.L of a difference between a value L of the
overcoat coating film and a value L of a color of a surface of the
metal sheet before the overcoat coating film is formed is 50 or
less, and the film thickness T of the overcoat coating film is 17
.mu.m or less.
22. The coated metal sheet according to claim 13, wherein the
coated metal sheet has a glossiness at 75 degrees of 1 to 25.
23. The coated metal sheet according to claim 13, wherein the
coated metal sheet is a coated metal sheet for exterior use.
24. An exterior building material composed of the coated metal
sheet according to claim 23.
25. The exterior building material according to claim 24, further
comprising one or more selected from the group consisting of
members to fix the exterior building material to a building,
members to connect a plurality of the exterior building materials,
marks that show a direction of the exterior building material on
mounting, and foam sheets or foam layers to improve thermal
insulation properties.
Description
TECHNICAL FIELD
The present invention relates to a coated metal sheet for exterior
use and an exterior building material.
BACKGROUND ART
Coated metal sheets, excellent in versatility, designability,
durability and the like, have been used in various applications. In
coated metal sheets for exterior building material applications,
mainly from the viewpoint of designability, a gloss adjusting agent
is usually blended in an overcoat coating film which is a surface
of the coated metal sheet surface. Silica is usually used as the
above-described gloss adjusting agent in the coated metal sheets
for exterior building materials. The particle diameter of the
silica is usually specified by an average particle diameter. The
average particle diameter of the silica as the gloss adjusting
agent in the coated metal sheet is usually from 3 to 30 .mu.m,
depending on the color and the application (for example, see PTL 1
(paragraph 0018)). Additionally, in order to provide the coating
film with unevenness to thereby provide the appearance and texture
of a so-called "matte coated steel sheet", it is necessary to
further add a matting agent having a particle diameter larger than
that of the gloss adjusting agent. Examples of the type of the
matting agent include glass beads, resin beads and the like. The
average particle diameter of the matting agent is usually from 10
to 50 .mu.m (for example, see PTL 2 (paragraph 0016)).
CITATION LIST
Patent Literature
PTL 1 Japanese Patent Application Laid-Open No. 2011-148107 PTL 2
Japanese Patent Application Laid-Open No. 2004-154993
SUMMARY OF INVENTION
Technical Problem
As coated metal sheets for exterior building materials,
chromate-coated steel sheets are used. Efforts have been made to
improve the molding processability or the corrosion resistance at
cut ends for the chromate-coated steel sheets, which thus have had
long-term durability. Meanwhile, strong interest has been shown to
environmental preservation in recent years also in the technical
field of exterior building materials. Accordingly, legal
regulations to ban the use of components that adversely affect or
cause a concern about possibility of adversely affecting the
environment have been under consideration. For example, total
prohibition of the use of hexavalent chromium components, generally
used in coated metal sheets as an anti-rust component, in the near
future is under consideration. Also for chromate-free coated steel
sheets, various considerations have been made such as pre-coating
treatment, optimization of anti-rust pigments and the like, and
characteristics obtained at molding processed portions and cut ends
are comparable to those of the chromate-coated steel sheets.
However, the corrosion resistance of the flat portion in
chromate-coated steel sheets did not lead to a large problem, while
corrosion in the flat portion in chromate-free coated steel sheets
may become severe. Particularly when silica is used as the
above-described gloss adjusting agent, corrosion such as stain
rust, coating film blistering and the like, in the flat portion has
occurred during actual use in some cases, before the intended age
of service, as shown in FIG. 1.
An object of the present invention is to provide a coated metal
sheet and an exterior building material that are chromate-free as
well as have excellent flat-portion corrosion resistance.
Solution to Problem
The present inventors have intensively studied causes of the
aforementioned corrosion in the flat portion. FIG. 2 is a
micrograph of a corroded portion in the flat portion of a
chromate-free coated metal sheet. In FIG. 2, portion A is a portion
where silica particles as a gloss adjusting agent are exposed from
the overcoat coating film, and portion B is a portion where the
silica particles have fallen off from the overcoat coating film.
FIG. 3 is a reflection electron micrograph of a cross section along
line L, in FIG. 2, in portion A of the above-described coated metal
sheet. FIG. 4 is a reflection electron micrograph of a cross
section along line L, in FIG. 2, in portion B of the
above-described coated metal sheet. FIG. 3 clearly shows the
occurrence of cracks at the silica particles exposed on the surface
of the overcoat coating film, and FIG. 4 clearly shows that
corrosion of the metal sheet originates from the holes in the
overcoat coating film from which the silica particles have fallen
off.
As described above, the present inventors have confirmed that, when
aggregated particles such as silica are used as the gloss adjusting
agent, the corrosion occurs in a portion where the gloss adjusting
agent in the overcoat coating film has cracked, collapsed, or
fallen off, and also that the gloss adjusting agent exposed from
the overcoat coating film to be worn in actual use cracks,
collapses and falls off the overcoat coating film.
The present inventors have also investigated the gloss adjusting
agent to thereby confirm that the silica specified by an average
particle diameter contains particles considerably larger than the
average particle diameter relative to the thickness of the overcoat
coating film. For example, when observing, among commercially
available silica to be used as the above-described gloss adjusting
agent, silica having an average particle diameter of 3.3 .mu.m with
an electron microscope, the present inventors have confirmed that
silica having a particle diameter of about 15 .mu.m is contained
(FIG. 5).
Similarly when aggregated particles such as silica,
polyacrylonitrile (PAN) and the like are used as a matting agent to
be additionally used in the overcoat coating film, the present
inventors have also confirmed that corrosion originates in a
portion where the matting agent exposed from the overcoat coating
film has cracked, collapsed, or fallen off (FIG. 6 and FIG. 7).
Then, the present inventors, focusing on the fact that such
aggregated particles having a large particle diameter decrease the
corrosion resistance, have found that, by use of a gloss adjusting
agent, which is aggregated particles having a specific particle
diameter relative to the thickness of the overcoat coating film,
and a matting agent, which is primary particles, corrosion
resistance can be obtained equivalent to or greater than the
corrosion resistance achieved by chromate-based chemical conversion
treatment and by use of a chromium-containing anti-rust pigment in
an undercoat coating film in conventional metal sheets, having
completed the present invention.
Specifically, the present invention relates to a chromate-free
coated metal sheet and an exterior building material.
[1] A coated metal sheet being chromate-free and including:
a metal sheet, and
an overcoat coating film to be disposed on the metal sheet,
wherein the overcoat coating film comprises a gloss adjusting agent
which is particles having micropores and a matting agent which is
primary particles,
wherein a content of the gloss adjusting agent in the overcoat
coating film is 0.2 to 15 vol %,
wherein a content of the matting agent in the overcoat coating film
is 0.2 to 15 vol %, and
wherein the coated metal sheet satisfies the following equations:
(R+2.sigma.1)/T.ltoreq.0.7 R1.gtoreq.2.0
2.0.ltoreq.(R2+2.sigma.2)/T.ltoreq.7.0 13.ltoreq.T.ltoreq.20
wherein R1 (.mu.m) is a number average particle diameter of the
gloss adjusting agent, R2 (.mu.m) is a number average particle
diameter of the matting agent, T (.mu.m) is a film thickness of the
overcoat coating film, .sigma.1 is a standard deviation of a number
particle size distribution of the gloss adjusting agent, and
.sigma.2 is a standard deviation of a number particle size
distribution of the matting agent.
[2] The coated metal sheet according to [1], further including an
undercoat coating film between the metal sheet and the overcoat
coating film.
[3] The coated metal sheet according to [1] or [2], wherein the
coated metal sheet is a coated metal sheet for exterior use.
[4] An exterior building material composed of the coated metal
sheet according to any one of [1] to [3].
Advantageous Effects of Invention
The present invention prevents exposure, cracking and the like of
the gloss adjusting agent, and cracking, fall-off and the like of
the matting agent, during the intended age of service. Accordingly,
there is provided a coated metal sheet for exterior use, wherein
the coated metal sheet is chromate-free as well as has excellent
flat-portion corrosion resistance equivalent to or greater than
that of coated metal sheets rust-prevented with chromium.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a micrograph of a corroded portion (coating film
blistering) occurred in the flat portion of a chromate-free coated
metal sheet in actual use of five years.
FIG. 2 is a micrograph of a corroded portion in the flat portion of
a chromate-free coated metal sheet.
FIG. 3 is a reflection electron micrograph of a cross section along
line L, in FIG. 2, in portion A of the coated metal sheet shown in
FIG. 2.
FIG. 4 is a reflection electron micrograph of a cross section along
line L, in FIG. 2, in portion B of the coated metal sheet shown in
FIG. 2.
FIG. 5 is an electron micrograph of silica powder having an average
particle diameter of 3.3 .mu.m.
FIG. 6 is a micrograph of a cross section of a corroded portion in
the flat portion of a chromate-free coated metal sheet in which
silica particles are used as a matting agent.
FIG. 7 is a micrograph of a cross section of a corroded portion in
the flat portion of a chromate-free coated metal sheet in which PAN
particles are used as a matting agent.
DESCRIPTION OF EMBODIMENTS
Hereinafter, the coated metal sheet according to one embodiment of
the present invention will be described. The above-described coated
metal sheet includes a metal sheet and an overcoat coating film to
be disposed on the metal sheet.
The above-described metal sheet can be selected from known metal
sheets in the range where the effect of the present embodiment can
be achieved. Examples of the metal sheet include cold-rolled steel
sheets, galvanized steel sheets, Zn--Al alloy-plated steel sheet,
Zn--Al--Mg alloy-plated steel sheets, aluminum-plated steel sheets,
stainless steel sheets (including austenitic, martensitic,
ferritic, and ferrite-martensite two-phase systems), aluminum
sheets, aluminum-alloy sheets, copper sheets and the like. The
above-described metal sheets are preferably plated steel sheets
from the viewpoint of corrosion resistance, lighter weight, and
cost-effectiveness. The plated steel sheet is preferably hot-dip
55% Al--Zn alloy-plated steel sheets, Zn--Al--Mg alloy-plated steel
sheets, or aluminum-plated steel sheets, particularly from the
viewpoint of corrosion resistance and from the viewpoint of
suitability for exterior building materials.
The above-described metal sheet preferably has a chemical
conversion film on its surface, from the viewpoint of improving the
adhesiveness of the coated metal sheet and the corrosion
resistance. Examples of the chemical conversion film include Ti--Mo
composite films, fluoro acid-based films, phosphate films,
resin-based films, resin and silane coupling agent-based films,
silica-based films, silica and silane coupling agent-based films,
zirconium-based films, and zirconium and silane coupling
agent-based films.
From the above-described viewpoint, the amount of the Ti--Mo
composite film deposited is preferably 10 to 500 mg/m.sup.2 in
terms of total Ti and Mo, the amount of the fluoro acid film
deposited is preferably 3 to 100 mg/m.sup.2 in terms of fluorine or
in terms of total elemental metals, and the amount of the phosphate
film deposited is preferably 0.1 to 5 g/m.sup.2 in terms of
elemental phosphorous, in the above-described metal sheet.
The amount of the above-described resin-based film deposited is
preferably 1 to 500 mg/m.sup.2 in terms of the resin, the amount of
the above-described resin and silane coupling agent-based film
deposited is preferably 0.1 to 50 mg/m.sup.2 in terms of Si, the
amount of the above-described silica-based film deposited is
preferably 0.1 to 200 mg/m.sup.2 in terms of Si, the amount of the
above-described silica and silane coupling agent-based film
deposited is preferably 0.1 to 200 mg/m.sup.2 in terms of Si, the
amount of the above-described zirconium-based film deposited is
preferably 0.1 to 100 mg/m.sup.2 in terms of Zr, and the amount of
the above-described zirconium and silane coupling agent-based film
deposited is preferably is 0.1 to 100 mg/m.sup.2 in terms of
Zr.
The above-described chemical conversion film can be formed by
applying an aqueous chemical conversion liquid for forming the film
by a known method such as roll-coating, spin-coating, spraying
methods and the like, to the above-described metal sheet surface
and drying the above-described metal sheet after application
without water washing. The drying temperature and the drying time
for the metal sheet are preferably 60 to 150.degree. C. as the
temperature which the metal sheet reaches and 2 to 10 seconds, for
example, from the viewpoint of productivity.
The above-described overcoat coating film is usually composed of
resin. The resin is selected as appropriate from the viewpoint of
designability, weather resistance and the like. Examples of the
resin include polyester, acrylic, urethane resins, and fluorine
resins.
The film thickness T of the above-described overcoat coating film
is 13 to 20 .mu.m. An extremely large film thickness T of the
overcoat coating film may be responsible for reduction in the
productivity, increase in the production cost and the like,
whereas, with an extremely small film thickness T, the intended
designability and the intended durability may not be achieved. For
example, in order to obtain a coated metal sheet that has good
productivity, exhibits the intended gloss and coloring, and can be
actually used as an exterior building material for at least 10
years, the film thickness T of the overcoat coating film is, for
example, preferably 14 .mu.m or more, more preferably 15 .mu.m or
more, from the above-described viewpoint. Also due to the
above-described reason, the film thickness T of the overcoat
coating film is preferably 19 .mu.m or less, more preferably 18
.mu.m or less. The film thickness T of the overcoat coating film
is, for example, the average value of distances from the bottom to
the surface at a plurality of positions on a portion where the
matting agent of the overcoat coating film is not present.
The film thickness T of the above-described overcoat coating film
is, from the viewpoint of the designability of the coated metal
sheet, preferably larger when a color of the overcoat coating film
is light, and can be smaller when the color of the overcoat coating
film is dark. Although it depends on the case, for example, when
the value L of the overcoat coating film is 80 or less, the film
thickness T of the overcoat coating film can be 15 .mu.m or less,
and when the value L of the overcoat coating film is more than 80,
the film thickness is preferably more than 15 .mu.m.
Alternatively, the film thickness T of the above-described overcoat
coating film can be smaller, as the color of the overcoat coating
film is closer to the color of the surface of the steel sheet
before the overcoat coating film is formed (for example, an
undercoat coating film described below), from the viewpoint of the
designability of the coated metal sheet. Although it depends on the
case, for example, when absolute value .DELTA.L of the difference
between the value L of the overcoat coating film and the value L of
the color of the surface of the steel sheet before the coating film
is formed is 10 or less, the film thickness T of the overcoat
coating film can be 13 .mu.m or less, when .DELTA.L is 20 or less,
the film thickness T can be 15 .mu.m or less, and when .DELTA.L is
50 or less, the film thickness T can be 17 .mu.m or less.
Incidentally, the above-described value L can be determined by
calculation by the Hunter's color difference formula from the
measurement result by a commercially available spectrophotometer
(for example, manufactured by KONICA MINOLTA OPTICS, INC.
"CM3700d").
The above-described overcoat coating film contains a gloss
adjusting agent. The gloss adjusting agent is blended in the
overcoat coating film to moderately roughen the surface of the
overcoat coating film, imparting the intended appearance with gloss
to the coated metal sheet. The gloss adjusting agent is also used
to adjust variation of gloss among production lots.
The above-described gloss adjusting agent has a number average
particle diameter R1 of 2.0 .mu.m or more. When the gloss adjusting
agent is extremely small, the gloss of the overcoat coating film is
extremely high, and thus, the intended designability may not be
achieved. As such, it is possible to determine the number average
particle diameter of the gloss adjusting agent R1 as appropriate
depending on the intended designability (glossiness) of the coated
metal sheet in the range where R1 satisfies the formula described
below. However, when R1 is extremely large, the roughness of the
overcoat coating film increases, and thus the intended
designability cannot be achieved. For example, in order to obtain a
coated metal sheet having a glossiness at 75 degrees of 1 to 25 in
addition to the flat-portion corrosion resistance, the number
average particle diameter R1 of the gloss adjusting agent is 3
.mu.m or more, 5 .mu.m or more, or 7 .mu.m or more, in the overcoat
coating film. The number average particle diameter can be confirmed
by observation of the cross-section of the overcoat coating film or
can be measured by an image analyzing method and the Coulter method
(for example, using an accurate particle sizing and counting
analyzer "Multisizer 4" manufactured by Beckman Coulter Inc.).
The content of the above-described gloss adjusting agent in the
above-described overcoat coating film is 0.2 to 15 vol %. When the
content is extremely high, the gloss of the overcoat coating film
becomes extremely low, and also, the processed-part adhesiveness
decreases. When the content is extremely low, the gloss cannot be
controlled. Thus, even if the content is extremely large or small,
the intended designability may not be achieved. For example, in
order to obtain a coated metal sheet having a glossiness at 75
degrees of 1 to 25, the content of the gloss adjusting agent in the
overcoat coating film is preferably 0.4 vol % or more, more
preferably 0.6 vol % or more. Also due to the above-described
reason, the content of the gloss adjusting agent in the overcoat
coating film is preferably 13 vol % or less, more preferably 11 vol
% or less. The content can be confirmed by measurement of the ash
content in the overcoat coating film, collection of the gloss
adjusting agent by dissolution of the overcoat coating film, image
analysis of a cross-sectional image of element discrimination
conducted at a plurality of points or the like.
The above-described gloss adjusting agent is particles having
micropores (hereinafter, may be referred to as "microporous
particles"). Examples of the microporous particles include
aggregates formed by chemical bonding of primary particles,
agglomerates formed by physical bonding of primary particles, and
porous particles. The porous particles have a porous structure at
least inside the particles. The above-described gloss adjusting
agent may be composed solely of the above-described microporous
particles or may contain particles other than microporous
particles. The microporous particles may be inorganic particles or
organic particles, and can be selected from known microporous
particles used as a gloss adjusting agent, in the range where the
particles satisfy the equation described below. Specific examples
of the materials of the microporous particles include silica,
calcium carbonate, barium sulfate, polyacrylonitrile, and calcium
carbonate-calcium phosphate composites.
The above-described coated metal sheet satisfies the following
equation: (R1+2.sigma.1)/T.ltoreq.0.7 wherein R1 (.mu.m) is the
number average particle diameter of the above-described gloss
adjusting agent, T (.mu.m) is the film thickness of the
above-described overcoat coating film, and .sigma.1 is the standard
deviation of the number particle size distribution of the
above-described gloss adjusting agent.
When the number particle size distribution of the above-described
gloss adjusting agent is the normal distribution, R1+2.sigma.1
represents the maximum value of the particle diameter of about
95.45% of the particles having a particle diameter larger than the
number average particle diameter R1. In this manner, R1+2.sigma.1
represents the substantially maximum value of the particle diameter
of the above-described gloss adjusting agent. With extremely large
(R1+2.sigma.1)/T, the intended flat portion-corrosion resistance
may not be achieved when the above-described microporous particles
is exposed due to wearing of the overcoat coating film during
actual use. With extremely small (R1+2.sigma.1)/T, the intended
glossiness may not be achieved. For example, in order to obtain a
coated metal sheet having an actual age of service as an exterior
building material of at least 10 years or more and a glossiness at
75 degrees of 1 to 25, (R1+2.sigma.1)/T is preferably 0.3 or more,
more preferably 0.4 or more. Also, due to the above-described
reason, (R1+2.sigma.1)/T is preferably 0.6 or less, more preferably
0.5 or less. R1 and .sigma.1 can be determined from the number
particle size distribution of the above-described gloss adjusting
agent.
The above-described gloss adjusting agent may be composed of
sufficiently small particles relative to the film thickness T of
the overcoat coating film when in the range satisfying the
above-described equation. From the viewpoint of preventing early
exposure of the gloss adjusting agent from the overcoat coating
film, the maximum value of the particle diameter in the number
particle size distribution of the gloss adjusting agent is
preferably less than the film thickness of the overcoat coating
film T, more preferably 0.7 T or less, still more preferably 0.6 T
or less. The gloss adjusting agent having the above-described
particle size distribution including the maximum value can be
selected from commercially-available products, or can be adjusted
by the following classification or the like.
The above-described gloss adjusting agent may be subjected to
classification to sharpen the particle size distribution of the
gloss adjusting agent, treatment to remove coarse particles in the
gloss adjusting agent or the like, from the viewpoint of preventing
wearing by its exposure from the overcoat coating film during
actual use of the exterior building material. The above-described
classification is conducted with, for example, a sieve, a forced
vortex-type centrifugal precision air classifier or the like.
Treatment for cutting the above-described coarse particles can be
conducted by a known method to separate and remove the
above-described coarse particles having a particle diameter of 0.3
T to 0.7 T, or a known method to pulverize the coarse
particles.
The above-described overcoat coating film also contain a matting
agent. The above-described matting agent is blended to the overcoat
coating film in order to exhibit unevenness that is larger than the
coarseness to be imparted by a gloss adjusting agent to the
overcoat coating film and can be visually confirmed and to impart a
texture, providing the coated metal sheet with the intended
appearance. The matting agent also includes those having a particle
diameter larger than the overcoat coating film, and thus can
prevent the overcoat coating film from being scratched. Thereby,
the scratch resistance of the coated metal sheet can be
improved.
Although the number average particle diameter of the
above-described matting agent R2 is not particularly limited, the
matting agent having an extremely small particle diameter cannot
reduce the gloss of the overcoat coating film, and the intended
designability may not be achieved. It is possible to determine the
number average particle diameter of the matting agent R2 as
appropriate depending on the intended designability (glossiness) of
the coated metal sheet in the range where R2 satisfies the equation
described below. However, when R2 is extremely large, the matting
agent causes streaks on coating, and the intended designability may
not be achieved. For example, in order to obtain a coated metal
sheet having a glossiness at 75 degrees of 1 to 25 in addition to
flat-portion corrosion resistance, the number average particle
diameter of the matting agent R2 is preferably 20 .mu.m or more,
more preferably 25 .mu.m or more. Also, due to the above-described
reason, the number average particle diameter of the matting agent
R2 is preferably 75 .mu.m or less, more preferably 50 .mu.m or
less, still more preferably 40 .mu.m or less. The number average
particle diameter can be confirmed by observation of the
cross-section of the overcoat coating film or can be measured by an
image analyzing method and the Coulter method (for example, using
an accurate particle sizing and counting analyzer "Multisizer 4"
manufactured by Beckman Coulter Inc.).
The content of the above-described matting agent in the
above-described overcoat coating film is 0.2 to 15 vol %. When the
content is extremely high, the gloss of the overcoat coating film
decreases, and also, the processed-part adhesiveness decreases. In
contrast, when the content is extremely low, gloss cannot be
adjusted, and in both cases, the intended designability may not be
achieved. For example, in order to obtain a coated metal sheet
having a glossiness at 75 degrees of 1 to 25, the content of the
matting agent in the overcoat coating film is preferably 0.4 vol %
or more, more preferably 0.6 vol % or more. Also due to the
above-described reason, the content of the matting agent in the
overcoat coating film is preferably 13 vol % or less, more
preferably 10 vol % or less. The content can be confirmed by
measurement of the ash content in the overcoat coating film,
collection of the matting agent by dissolution of the overcoat
coating film, image analysis of a cross-sectional image of element
discrimination conducted at a plurality of points or the like.
The above-described matting agent is primary particles. The primary
particles refer to particles having no micropores that may cause
the particles to collapse when the substance (for example, water)
present in their voids expands. The primary particles may be resin
particles or inorganic particles, and can be selected from known
primary particles used as a matting agent, in the range where the
particles satisfy the equation described below. Specific examples
of the primary particles include primary particles composed of
resin such as acrylic resin, polyurethane resin, polyester resin,
melamine resin, urea resin, polyamide resin and the like (resin
particles); and primary particles composed of an inorganic compound
such as glass, silicon carbide, boron nitride, zirconia, alumina,
silica, and the like (inorganic particles). The shape of these
primary particles is preferably approximately spherical, but may be
other shape such as a cylindrical shape, a disc shape and the like.
Also, recesses and the like may be present on the surface of the
primary particles unless they are micropores that may become an
origin of collapse of the particles.
The above-described coated metal sheet satisfies the following
equation: 2.0.ltoreq.(R2+2.sigma.2)/T.ltoreq.7.0 wherein R2 (.mu.m)
is the number average particle diameter of the above-described
matting agent, T (.mu.m) is the film thickness of the
above-described overcoat coating film, and .sigma.2 is the standard
deviation of the number particle size distribution of the
above-described matting agent.
When the number particle size distribution of the above-described
matting agent is the normal distribution, R2+2.sigma.2 represents
the maximum value of the particle diameter of about 95.45% of the
particles having a particle diameter larger than the number average
particle diameter R2. In this manner, R2+2.sigma.2 represents the
substantially maximum value of the particle diameter of the
above-described matting agent. When (R2+2.sigma.2)/T is extremely
large, streaks or the like attributable to the matting agent occur
on coating of the overcoat coating film, and a fair coating
appearance may not be achieved. When (R2+2.sigma.2)/T is extremely
small, the intended texture may not be achieved. For example, in
order to obtain a coated metal sheet having a glossiness at 75
degrees of 1 to 25, in an overcoat coating film having an actual
age of service as an exterior building material of at least 10
years or more and containing a gloss adjusting agent and a matting
agent, (R2+2.sigma.2)/T is preferably 3 or more, more preferably 4
or more. Also, due to the above-described reason, (R2+2.sigma.2)/T
is preferably 6 or less, more preferably 5 or less. R2 and .sigma.2
can be determined from the number particle size distribution of the
above-described matting agent.
The above-described overcoat coating film may further contain other
ingredients besides the resin, gloss adjusting agent, and matting
agent aforementioned, in the range where the effect of the present
embodiment can be achieved. For example, the overcoat coating film
may further contain a colorant. Examples of the colorant include
inorganic pigments such as titanium oxide, calcium carbonate,
carbon black, iron black, iron oxide yellow, titanium yellow,
colcothar, iron blue, cobalt blue, cerulean blue, ultramarine blue,
cobalt green, molybdenum red and the like; composite oxide calcined
pigments containing metal components such as CoAl, CoCrAl,
CoCrZnMgAl, CoNiZnTi, CoCrZnTi, NiSbTi, CrSbTi, FeCrZnNi, MnSbTi,
FeCr, FeCrNi, FeNi, FeCrNiMn, CoCr, Mn, Co, SnZnTi and the like;
metallic pigments such as Al, resin-coated Al, Ni and the like; and
organic pigments such as Quinacridone Red, Lithol Red B, Brilliant
Scarlet G, Pigment Scarlet 3B, Brilliant Carmine 6B, Lake Red C,
Lake Red D, Permanent Red 4R, Bordeaux 10B, Fast Yellow G, Fast
Yellow 10G, Pare Red, Watching Red, Benzidine Yellow, Benzidine
Orange, Bon Maroon L, Bon Maroon M, Brilliant Fast Scarlet,
Vermilion Red, Phthalocyanine Blue, Phthalocyanine Green, Fast
Skyblue, Aniline Black and the like. The above-described colorant
is sufficiently smaller relative to the above-described gloss
adjusting agent, and, for example, the number average particle
diameter of the above-described colorant is 0.01 to 1.5 .mu.m. The
content of the colorant in the overcoat coating film is, for
example, 2 to 20 vol %.
The above-described overcoat coating film may further contain an
extender pigment. Examples of the extender pigment include barium
sulfate, titanium oxide and the like. The above-described extender
pigment is sufficiently smaller relative to the above-described
gloss adjusting agent, and, for example, the number average
particle diameter of the above-described extender pigment is 0.01
to 1 .mu.m. The content of the extender pigment in the overcoat
coating film is, for example, 0.1 to 15 vol %.
The above-described overcoat coating film may further contain a
lubricant, from the viewpoint of preventing the occurrence of
galling in the overcoat coating film on processing the coated metal
sheet. Example of the lubricant include organic waxes such as
fluorine-based wax, polyethylene-based wax, styrene-based wax,
polypropylene-based wax and the like, and inorganic lubricants such
as molybdenum disulfide, talc and the like. The content of the
lubricant in the overcoat coating film is, for example, 0 to 10 vol
%.
The above-described overcoat coating film is produced by a known
method that includes applying a coating material for overcoat
coating films to the surface of the above-described metal sheet,
the surface of the undercoat coating film described below or the
like, drying the coating material, and curing the coating material
as required. The coating material for overcoat coating films
contains materials for the overcoat coating film aforementioned,
and may further contain other ingredients besides the materials in
the range where the effect of the present embodiment can be
achieved.
For example, the coating material for overcoat coating films may
further contain a curing agent. The above-described curing agent
crosslinks the polyester or acrylic resin aforementioned on curing
(baking) when the overcoat coating film is produced. The type of
the curing agent can be selected from the crosslinking agent
aforementioned and known curing agents as appropriate, depending on
the type of the resin to be used, baking conditions and the
like.
Examples of the above-described curing agent include melamine
compounds, isocyanate compounds, combinations of a melamine
compound and an isocyanate compound and the like. Examples of the
melamine compound include imino group-type, methylol-imino
group-type, methylol group-type, or complete alkyl group-type
melamine compounds. The isocyanate compound may be any of aromatic,
aliphatic, and alicyclic compounds, and examples include m-xylene
diisocyanate, hexamethylene diisocyanate, naphthalene diisocyanate,
isophorone diisocyanate, and block compounds of these.
The overcoat coating film may further contain a curing catalyst as
appropriate in the range where the storage stability of the coating
material for overcoat coating films is not affected. The content of
the above-described curing agent in the overcoat coating film is
for example, 10 to 30 vol %.
The overcoat coating film may also contain 10 vol % or less of an
ultraviolet absorber (UVA), a light stabilizer (HALS) and the like
as appropriate, from the viewpoint of further improving the weather
resistance. Furthermore, the overcoat coating film may contain a
hydrophilizing agent, for example, 30 vol % or more of a partially
hydrolyzed condensate of tetraalkoxysilane or the like, from the
viewpoint of prevention of rain streak stains.
The above-described coating material for overcoat coating films is
prepared by, for example, dispersing the materials for the overcoat
coating film aforementioned in a solvent. The coating material may
contain a solvent, a crosslinking agent and the like. Examples of
the above-described solvent include hydrocarbons such as toluene,
xylene and the like; esters such as ethyl acetate, butyl acetate
and the like; ethers such as cellosolve and the like; and ketones
such as methyl isobutyl ketone, methyl ethyl ketone, isophorone,
cyclohexanone and the like.
The above-described coating material for overcoat coating films is
applied, for example, by a known method such as roll coating,
curtain flow coating, spray coating, immersion coating and the
like. The overcoat coating film is produced by heating a metal
sheet to which a coating material for overcoat coating film has
been applied such that the temperature of the metal sheet reaches
200 to 250.degree. C. thereby baking the above-described coating
material for overcoat coating films onto the metal sheet. The film
thickness T of the overcoat coating film is adjusted as
appropriate, depending on, for example, the amount of the
above-described coating material coated.
Incidentally, as aforementioned, blending a matting agent into the
overcoat coating film allows a unique design to be exhibited as
well as can improve the scratch resistance of the coated metal
sheet. In order to achieve both the designability and the scratch
resistance, the overcoat coating film is preferably coated thicker
than a coating film that contains a gloss adjusting agent only and
contains no matting agent. Also, since the ratio of nonvolatile
ingredients in the is the coating material increases by blending a
matting agent into the overcoat coating film, the overcoat coating
film can be coated thicker than a coating film that contains a
gloss adjusting agent only and contains no matting agent.
The above-described coated metal sheet may have further components,
in the range where the effect of the present embodiment can be
exerted. For example, the above-described coated metal sheet
preferably further has an undercoat coating film between the
above-described metal sheet and the overcoat coating film, from the
viewpoint of improving the adhesiveness and the corrosion
resistance of the overcoat coating film in the coated metal sheet.
The above-described undercoat coating film is disposed on the
surface of the metal sheet, or, when the above-described chemical
conversion film has been made, on the surface of the chemical
conversion film.
The above-described undercoat coating film is composed of resin.
Examples of the resin include epoxy resin, polyester,
epoxy-modified polyester resin, acrylic resin, and phenoxy
resin.
The above-described undercoat coating film may further contain an
anti-rust pigment, a coloring pigment, a metallic pigment, an
extender pigment or the like. Examples of the above-described
anti-rust pigment include non-chromium-based anti-rust pigments
such as modified silica, vanadates, magnesium hydrogenphosphate,
magnesium phosphate, zinc phosphate, aluminum polyphosphate and the
like. Example of the above-described coloring pigment include
titanium oxide, carbon black, chromium oxide, iron oxide,
colcothar, titanium yellow, cobalt blue, cobalt green, Aniline
Black, and Phthalocyanine Blue. Example of the above-described
metallic pigment include aluminum flakes (non-leafing type), bronze
flakes, copper flakes, stainless steel flakes, and nickel flakes.
Examples of the above-described extender pigment include barium
sulfate, titanium oxide, silica, and calcium carbonate.
The content of the above-described pigment in the undercoat coating
film can be determined as appropriate, in the range where the
effect of the present embodiment can be achieved. For example, the
content of the above-described anti-rust pigment in the
above-described undercoat coating film is preferably, for example,
10 to 70 vol %.
The above-described undercoat coating film is produced by
application of a coating material for undercoat coating films. The
coating material may contain a solvent, a crosslinking agent and
the like. Examples of the above-described solvent include
hydrocarbons such as toluene xylene and the like; esters such as
ethyl acetate, butyl acetate and the like; ethers such as
cellosolve and the like; and ketones such as methyl isobutyl
ketone, methyl ethyl ketone, isophorone, cyclohexanone and the
like. Examples of the above-described crosslinking agent include
melamine resin, isocyanate resin and the like for crosslinking the
resin aforementioned. The coating material for undercoat coating
films is prepared by homogeneously mixing and dispersing the
materials aforementioned.
The coating material for undercoat coating films is applied by a
known method such as roll coating, curtain flow coating, spray
coating, immersion coating or the like to a metal sheet in an
amount to be coated such that a dry film thickness of 1 to 10
.mu.m, preferably 3 to 7 .mu.m is obtained. A coating film of the
coating material is produced by heating a metal sheet at, for
example, 180 to 240.degree. C., a temperature which the metal sheet
achieves, thereby baking the film onto the metal sheet.
The coated metal sheet according to the present embodiment is a
chromate-free coated metal sheet. "Chromate-free" means that the
above-described coated metal sheet contains substantially no
hexavalent chromium. It is possible to confirm that the
above-described coated metal sheet is "chromate-free" as follows.
For example, in any of the metal sheet, the chemical conversion
film, the undercoat coating film, and the overcoat coating film
aforementioned, four 50 mm.times.50 mm specimens are cut off from a
metal sheet on which the overcoat coating film or the undercoat
coating film has been produced singly, and the specimens are
immersed in 100 mL of boiling pure water for 10 minutes. Then, when
hexavalent chromium eluted in pure water is quantified by a
concentration analysis method in compliance with JIS H8625, Annex
2. 4. 1, "Diphenylcarbazide Visual Colorimetric Method", the
concentration shall be lower than the detection limit Hexavalent
chromium is not eluted form the above-described coated metal sheet
during actual use into the environment, and the above-described
coated metal sheet exhibits sufficient corrosion resistance at its
flat portion. Incidentally, a "flat portion" refers to a portion
that is covered with the above-described overcoat coating film of
the above-described metal sheet and has not been deformed by
bending, drawing, bulging, embossing, roll-forming or the like.
Applications of the above-described coated metal sheet are suitable
for exterior use. "For exterior use" refers to being used in
portions exposed to the open air such as roofs, walls, accessories,
signboards, outdoor-installed apparatuses and the like, wherein the
portions may be irradiated with a sunbeam and its reflected light.
Examples of the coated metal sheet for exterior use include coated
metal sheets for exterior building materials and the like.
The above-described coated metal sheet is suitable for a matte
coated metal sheet. Matte refers to glossiness at 75 degrees being
1 to 25. The above-described glossiness is adjusted with the
average particle diameter of the gloss adjusting agent and matting
agent, their contents in the overcoat coating film and the
like.
In the above-described coated metal sheet, the above-described
gloss adjusting agent (microporous particles) are included
completely in the overcoat coating film. Also, the substantially
maximum particle of the microporous particles is sufficiently
smaller relative to the film thickness of the overcoat coating
film. Thus, the above-described overcoat coating film can be
designed such that the above-described microporous particles are
not exposed within the intended age of service, even if the resin
in the overcoat coating film is gradually worn from the surface of
the overcoat coating film by actual use in an exterior application.
Therefore, cracking and collapse of the above-described microporous
particles and fall-off from the above-described overcoat coating
film within the intended age of service are prevented, and
corrosive factors such as rainwater and the like cannot reach the
metal sheet during the intended age of service.
Meanwhile, in the above-described coated metal sheet, although the
matting agent is covered with the resin constituting the overcoat
coating film, at least a part of the particles in the matting agent
is larger than the film thickness of a portion of the overcoat
coating film where the matting agent is not contained. Thus, the
matting agent may appear from the overcoat coating film when the
resin in the overcoat coating film is gradually worn from the
surface of the overcoat coating film by actual use in an exterior
application, even during the intended age of service. In such a
situation, if microporous particles as the matting agent are
blended in the overcoat coating film, a portion of the overcoat
coating film where the matting agent cracks, collapses, or falls
off may become an origin of corrosion. Thus, primary particles are
blended as the matting agent in the above-described coated metal
sheet. Therefore, even if the above-described primary particles
appear from the surface of the overcoat coating film by actual use
in an exterior application, cracking and collapse as those
occurring in microporous particles and fall-off from the
above-described overcoat coating film are prevented, and corrosive
factors such as rainwater cannot reach the metal sheet.
Thus, the above-described coated metal sheet is chromate-free as
well as exhibits flat portion-corrosion resistance equivalent to or
greater than that of coated metal sheets containing a
chromate-based anti-rust component.
As clear from the above description, according to the present
embodiment, there can be provided a coated metal sheet that is
chromate-free as well as has excellent flat-portion corrosion
resistance, wherein the coated metal sheet has a metal sheet and an
overcoat coating film to be disposed on the metal sheet, wherein
the overcoat coating film contains particles having micropores
(microporous particles) as a gloss adjusting agent and primary
particles as a matting agent, wherein the content of the
above-described gloss adjusting agent in the above-described
overcoat coating film is 0.2 to 15 vol %, and the content of the
above-described matting agent in the above-described overcoat
coating film is 0.2 to 15 vol %, and wherein the following
equations are satisfied: (R1+2.sigma.1)/T.ltoreq.0.7 R1.gtoreq.2.0
2.0.ltoreq.(R2+2.sigma.2)/T.ltoreq.7.0 13.ltoreq.T.ltoreq.20
wherein R1 (.mu.m) is the number average particle diameter of the
gloss adjusting agent, R2 (.mu.m) is the number average particle
diameter of the matting agent, T (.mu.m) is the film thickness of
the above-described overcoat coating film, .sigma.1 is the standard
deviation of the number particle size distribution of the
above-described microporous particles, and .sigma.2 is the standard
deviation of the number particle size distribution of the
above-described primary particles.
Additionally, that the above-described coated metal sheet further
has an undercoat coating film between the above-described metal
sheet and the above-described overcoat coating film is further
effective from the viewpoint of improving the adhesiveness and
corrosion resistance of the overcoat coating film in the coated
metal sheet.
Additionally, that the above-described coated metal sheet is a
coated metal sheet for exterior use is further effective from the
viewpoint of reducing a load due to elution of chromium during
actual use on the environment.
An exterior building material composed of the above-described
coated metal sheet is chromate-free as well as can exhibit
excellent flat portion-corrosion resistance during actual use of 10
years or more.
The above-described coated metal sheet is formed into an exterior
building material by known processing such as bending, drawing,
bulging, embossing, roll-forming or the like. In this manner, the
exterior building material is composed of the above-described
coated metal sheet. The exterior building material may further
include other structure in the range where the above-described
effects can be achieved. For example, the above-described exterior
building material may further have a structure to be subjected to
appropriate installation during actual use of the exterior building
material. Examples of such a structure include members to fix an
exterior building material to a building, members to connect a
plurality of exterior building materials, marks that show the
direction of an exterior building material on mounting, foam sheets
and foam layers to improve the thermal insulation properties and
the like. These structures may be included in the coated metal
sheet for exterior use aforementioned.
Hereinafter, the present invention will be described in more detail
with reference to Examples, but the present invention is not
limited by these Examples.
EXAMPLES
[Production of Coated Base Sheets 1 to 3]
A hot-dip 55% Al--Zn alloy-plated steel sheet having an amount
deposited on both the sides of 150 g/m.sup.2 was alkali-degreased,
and "SURFCOAT NRC300NS" manufactured by Nippon Paint Co., Ltd.
("SURFCOAT" is a registered trademark of the company), which is a
chromate treatment solution, at 20.degree. C. was applied to the
surface of the plated layer of the plated steel sheet, as
pre-coating treatment. The plated steel sheet was dried at
100.degree. C. without washing with water to thereby obtain a
chromate-treated steel sheet having an amount deposited of 20
mg/m.sup.2 in terms of chromium. Additionally, the following
chromate-free treatment solution, instead of the above-described
chromate treatment solution, was applied, and the plated steel
sheet was dried at 100.degree. C. without washing with water to
thereby obtain a chromate-free chemical conversion steel sheet
having an amount deposited of 10 mg/m.sup.2 in terms of Ti.
TABLE-US-00001 (Chromate-free treatment solution)
Hexafluorotitanate 55 g/L Hexafluorozirconate 10 g/L
Aminomethyl-substituted polyvinyl phenol 72 g/L Water Balance
To the surface of the above-described chromate-free chemical
conversion steel sheet, the following undercoat coating material 1
based on epoxy resin was applied. The above-described chemical
conversion steel sheet was heated such that the temperature of the
above-described plated steel sheet reached 200.degree. C. to
thereby obtain chromate-free coated base sheet 1 that had undercoat
coating film 1 having a chromate-free dry film thickness of 5
.mu.m. Additionally, chromate-free coated base sheet 2 that had a
chromate-free undercoat coating film 2 having a dry film thickness
of 5 .mu.m was obtained in the same manner as coated base sheet 1
except that the following undercoat coating material 2 was used
instead of undercoat coating material 1. Furthermore,
chromium-containing coated base sheet 3 that had a
chromium-containing undercoat coating film 3 having a dry film
thickness of 5 .mu.m was obtained in the same manner as coated base
sheet 1 except that the above-described chromate-treated steel
sheet was used instead of the above-described chromate-free
chemical conversion steel sheet and that the following undercoat
coating material 3 was used instead of undercoat coating material 1
was used.
TABLE-US-00002 (Undercoat coating material 1) Phosphate mixture 15
vol % Barium sulfate 5 vol % Silica 1 vol % Clear coating material
Balance
TABLE-US-00003 (Undercoat coating material 2) Calcium vanadate 15
vol % Barium sulfate 5 vol % Silica 1 vol % Clear coating material
Balance
TABLE-US-00004 (Undercoat coating material 3) Strontium chromate 15
vol % Barium sulfate 5 vol % Silica 1 vol % Clear coating material
Balance
In the above-described undercoat coating materials 1 to 3, the
above-described clear coating material is "NSC680" manufactured by
Nippon Fine Coatings Co., Ltd. In the above-described undercoat
coating material 1, the above-described phosphate mixture is a
mixture of magnesium hydrogenphosphate, magnesium phosphate, zinc
phosphate, and aluminum tripolyphosphate. Additionally, the
above-described vol % is a proportion based on the solid content in
the undercoat coating material.
[Preparation of Overcoat Coating Material]
Overcoat coating materials 1 to 3 having the following composition
were prepared. The clear coating material described below in
overcoat coating material 1 is "CA clear coating material"
manufactured by Nippon Fine Coatings Co., Ltd., the clear coating
material described below in overcoat coating material 2 is "QK
clear coating material" manufactured by the company, and the clear
coating material described below in overcoat coating material 3 is
"NSC3300clear coating material" manufactured by the company. Carbon
black is a coloring pigment. The vol % described below is a
proportion based on the solid content in the overcoat coating
material.
TABLE-US-00005 (Overcoat coating material) Carbon black 7 vol %
Gloss adjusting agent (the type and the amount blended are shown in
Tables 1 to 3) Matting agent (the type and the amount blended are
shown in Tables 1 to 3) Clear coating material Balance
[Production of Coated Metal Sheets 1 to 13]
Overcoat coating material 1, prepared by blending 0.2 vol % of
silica particles A' (silica A') ("'" indicates that the silica has
been classified) as the gloss adjusting agent and 5 vol % of
acrylic particles A (acrylic A) as the matting agent, was applied
to the surface of undercoat coating film 1 of coated base sheet 1.
The coated base sheet 1 was heated such that the temperature of the
above-described plated steel sheet in coated base sheet 1 reached
220.degree. C. to thereby produce an overcoat coating film having a
dry film thickness T of 15 .mu.m. Coated metal sheet 1 was thus
produced.
Silica particles A' are powder prepared by cutting particles having
a particle diameter of 0.3 T or more from "NIPGEL AZ-400"
manufactured by Tosoh Silica Corporation ("NIPGEL is a registered
trademark of the company) with a forced vortex-type centrifugal
precision air classifier. "NIPGEL AZ-400", which has been produced
by a wet gel method, corresponds to the aforementioned microporous
particles. As determined with "Multisizer 4" manufactured by
Beckman Coulter Inc. using an aperture tube having a diameter of 50
.mu.m, when the film thickness T was 15 .mu.m, the silica particles
A' have an average particle diameter R1 of 2.5 .mu.m, the standard
deviation .sigma.1 being 1.0 .mu.m.
Acrylic particles A used were "TAFTIC AR-650MX" manufactured by
Toyobo Co., Ltd. ("TAFTIC" is a registered trademark of the
company.). "TAFTIC AR-650MX", which has been produced by suspension
polymerization, corresponds to the aforementioned primary
particles. As determined with "Multisizer 4" manufactured by
Beckman Coulter Inc. using an aperture tube having a diameter of 50
.mu.m, acrylic particles A have an average particle diameter R2 of
40 .mu.m, the standard deviation .sigma.2 being 4 .mu.m.
Coated metal sheets 2 to 4 were each produced in the same manner as
coated metal sheet 1 except that the amount of silica particles A'
blended was changed as shown in Table 1. Coated metal sheets 5 to 7
were each produced in the same manner as coated metal sheet 1
except that the amount of acrylic particles A blended was changed
as shown in Table 1. Additionally, coated metal sheets 8 to 10 were
each produced in the same manner as coated metal sheet 2 except
that the dry film thickness T was changed as shown in Table 1. When
the film thickness T is 13 .mu.m, silica particles A' have an
average particle diameter R1 of 2.2 .mu.m, the standard deviation
.sigma.1 being 0.9 .mu.m. When the film thickness T is 17 .mu.m,
silica particles A' have an average particle diameter R1 of 2.8
.mu.m, the standard deviation al being 1.1 .mu.m. When the film
thickness T is 20 .mu.m, silica particles A' have an average
particle diameter R1 of 3.0 .mu.m, the standard deviation al being
1.5 .mu.m. Additionally, coated metal sheet 11 was produced in the
same manner as coated metal sheet 2 except that the type of the
coated base sheet was changed as shown in Table 1. Furthermore,
coated metal sheets 12 and 13 were each produced in the same manner
as coated metal sheet 2 except that the type of the overcoat
coating material was changed as shown in Table 1.
Incidentally, coated metal sheet 2 was cut to allow its cross
section to be exposed. The cross section was placed inside a mass
of epoxy resin, further ground the above described cross section,
and photographed with a scanning electron microscope. The resulting
image of a plurality of spots was processed and analyzed to
determine the particle size distribution of silica particles A' and
acrylic particles A. R1, .sigma.1, R2, and .sigma.2 were confirmed
to be substantially equivalent to the above-described numerical
values.
[Production of Coated Metal Sheets 14 to 26]
Coated metal sheet 14 was produced in the same manner as coated
metal sheet 1 except that overcoat coating material 1 to which 0.2
vol % of silica particles B'(silica B') was blended as the gloss
adjusting agent was used.
Silica particles B' are powder prepared by cutting particles having
a particle diameter of 0.2 T or more from "Sylysia 300P"
manufactured by Fuji Silysia Chemical Ltd. with a forced
vortex-type centrifugal precision air classifier. "Sylysia 300P",
which has been produced by a wet gel method, corresponds to the
aforementioned microporous particles. When the film thickness T is
15 .mu.m, silica particles B' have an average particle diameter R1
of 2 .mu.m, the standard deviation al being 0.5 .mu.m.
Coated metal sheets 15 to 17 were each produced in the same manner
as coated metal sheet 14 except that the amount of silica particles
B' blended was changed as shown in Table 1. Additionally, coated
metal sheets 18 to 20 were each produced in the same manner as
coated metal sheet 15 except that the amount of acrylic particles A
blended was changed as shown in Table 1. Additionally, coated metal
sheets 21 to 23 were each produced in the same manner as coated
metal sheet 15 except that the dry film thickness T was changed as
shown in Table 1. When the film thickness T is 13 .mu.m, silica
particles B' have an average particle diameter R1 of 1.9 .mu.m, the
standard deviation .sigma.1 being 0.4 .mu.m. When the film
thickness T is 17 .mu.m, silica particles B' have an average
particle diameter R1 of 2.1 .mu.m, the standard deviation .sigma.1
being 0.7 .mu.m. When the film thickness T is 20 .mu.m, silica
particles B' have an average particle diameter R1 of 2.2 .mu.m, the
standard deviation .sigma.1 being 0.8 .mu.m. Additionally, coated
metal sheet 24 was produced in the same manner as coated metal
sheet 15 except that the type of the coated base sheet was changed
as shown in Table 2. Furthermore, coated metal sheets 25 and 26
were each produced in the same manner as coated metal sheet 15
except that the type of the overcoat coating material was changed
as shown in Table 2.
[Production of Coated Metal Sheets 27 to 32]
Coated metal sheet 27 was produced in the same manner as coated
metal sheet 15 except that silica particles C' (silica C') were
used as the gloss adjusting agent instead of silica particles B'.
Silica particles C' are powder prepared by cutting particles having
a particle diameter of 0.5 T or more from "NIPGEL AZ-410"
manufactured by Tosoh Silica Corporation with a forced vortex-type
centrifugal precision air classifier. "NIPGEL AZ-410", which has
been produced by a wet gel method followed by treatment with
inorganic material, corresponds to the aforementioned microporous
particles. When the film thickness T is 15 .mu.m, silica particles
C' have an average particle diameter R1 of 3.5 .mu.m, the standard
deviation al being 2.2 .mu.m.
Additionally, coated metal sheet 28 was produced in the same manner
as coated metal sheet 15 except that silica particles D' (silica
D') were used as the gloss adjusting agent instead of silica
particles B'. Silica particles D' are powder prepared by cutting
particles having a particle diameter of 0.5 T or more from "NIPGEL
AZ-460" manufactured by Tosoh Silica Corporation with a forced
vortex-type centrifugal precision air classifier. "NIPGEL AZ-460",
which has been produced by a wet gel method followed by treatment
with organic material, corresponds to the aforementioned
microporous particles. When the film thickness T is 15 .mu.m,
silica particles D' have an average particle diameter R1 of 3.7
.mu.m, the standard deviation al being 2.1 .mu.m.
Additionally, coated metal sheet 29 was produced in the same manner
as coated metal sheet 15 except that silica particles E' (silica
E') were used as the gloss adjusting agent instead of silica
particles B'. Silica particles E' are powder prepared by cutting
particles having a particle diameter of 0.7 T or more from "ACEMATT
TS 100" manufactured by NIPPON AEROSIL CO., LTD. ("ACEMATT" is a
registered trademark of Evonik Degussa GmbH) with a forced
vortex-type centrifugal precision air classifier. "ACEMATTTS 100",
which has been produced by a dry combustion method, corresponds to
the aforementioned microporous particles. When the film thickness T
is 13 .mu.m, silica particles E' have an average particle diameter
R1 of 7.9 .mu.m, the standard deviation al being 0.6 .mu.m.
Additionally, coated metal sheet 30 was produced in the same manner
as coated metal sheet 15 except that silica particles F (silica F)
were used as the gloss adjusting agent instead of silica particles
B'. Silica particles F are powder prepared by cutting particles
having a particle diameter of 0.7 T or more from "ACEMATT 3300"
manufactured by NIPPON AEROSIL CO., LTD. with a forced vortex-type
centrifugal precision air classifier. "ACEMATT 3300", which has
been produced by a dry combustion method followed by treatment with
organic material, corresponds to the aforementioned microporous
particles. When the film thickness T is 13 .mu.m, silica particles
F' have an average particle diameter R1 of 7.5 .mu.m, the standard
deviation .sigma.1 being 0.8 .mu.m.
Additionally, coated metal sheet 31 was produced in the same manner
as coated metal sheet 2 except that overcoat coating material 1 to
which 5 vol % of polyacrylonitrile particles A' (PAN A') was
blended as the gloss adjusting agent was used.
PAN particles A' are powder prepared by cutting particles having a
particle diameter of 0.4 T or more from "TAFTIC ASF-7" manufactured
by Toyobo Co., Ltd. with a forced vortex-type centrifugal precision
air classifier. "TAFTIC ASF-7", which has been produced by
pulverizing particles prepared by a spray dry method, corresponds
to the aforementioned microporous particles. When the film
thickness T is 15 .mu.m, PAN particles A' have an average particle
diameter R1 of 5 .mu.m, the standard deviation .sigma.1 being 0.6
.mu.m.
Additionally, coated metal sheet 32 was produced in the same manner
as coated metal sheet 2 except that overcoat coating material 1 to
which 5 vol % of calcium carbonate-calcium phosphate composite
particles A' (CaCPC A') was blended as the gloss adjusting agent
was used.
CaCPC particles A' are powder prepared by cutting particles having
a particle diameter of 0.4 T or more from "Poronex" manufactured by
MARUO CALCIUM CO., LTD. ("Poronex" is a registered trademark of the
company) with a forced vortex-type centrifugal precision air
classifier. "Poronex", which has a petal-like porous structure,
corresponds to the aforementioned microporous particles. When the
film thickness T is 15 .mu.m, CaCPC particles A' have an average
particle diameter R1 of 5 .mu.m, the standard deviation al being
0.5 .mu.m.
[Production of Coated Metal Sheets 33 to 36]
Coated metal sheet 33 was produced in the same manner as coated
metal sheet 15 except that urethane particles (urethane) were used
as the matting agent instead of acrylic particles A. The urethane
particles used were "Art Pearl C-200" manufactured by Negami
Chemical Industrial Co., Ltd. ("Art Pearl" is a registered
trademark of the company.). "Art Pearl C-200", which has been
produced by suspension polymerization, corresponds to the
aforementioned primary particles. As determined with "Multisizer 4"
manufactured by Beckman Coulter Inc. using an aperture tube having
a diameter of 50 .mu.m, the urethane particles have an average
particle diameter R2 of 30 .mu.m, the standard deviation .sigma.2
being 3 .mu.m.
Additionally, coated metal sheet 34 was produced in the same manner
as coated metal sheet 33 except that glass particles (glass) were
used as the matting agent instead of the urethane particles. The
glass particles used were "EGB731" manufactured by
Potters-Ballotini Co., Ltd. "EGB731" corresponds to the
aforementioned primary particles. As determined with "Multisizer 4"
manufactured by Beckman Coulter Inc. using an aperture tube having
a diameter of 50 .mu.m, the glass particles have an average
particle diameter R2 of 20 .mu.m, the standard deviation .sigma.2
being 5 .mu.m.
Additionally, coated metal sheet 35 was produced in the same manner
as coated metal sheet 33 except that acrylic particles B (acrylic
B) was used as the matting agent instead of the urethane particles.
Acrylic particles B used were "TAFTIC AR650MZ" manufactured by
Toyobo Co., Ltd. As determined with "Multisizer 4" manufactured by
Beckman Coulter Inc. using an aperture tube having a diameter of 50
.mu.m, acrylic particles B have an average particle diameter R2 of
60 .mu.m, the standard deviation .sigma.2 being 5 .mu.m.
Additionally, coated metal sheet 36 was produced in the same manner
as coated metal sheet 33 except that acrylic particles C (acrylic
C) were used as the matting agent instead of the urethane
particles. Acrylic particles C used were "TAFTIC AR650ML"
manufactured by Toyobo Co., Ltd. "TAFTIC AR650ML", which has been
produced by suspension polymerization, corresponds to the
aforementioned primary particles. As determined with "Multisizer 4"
manufactured by Beckman Coulter Inc. using an aperture tube having
a diameter of 50 .mu.m, acrylic particles C have an average
particle diameter R2 of 75 .mu.m, the standard deviation .sigma.2
being 15 .mu.m.
[Production of Coated Metal Sheets 37 to 43]
Coated metal sheet 37 was produced in the same manner as coated
metal sheet 1 except that silica particles G (silica G), which were
prepared by the method described below, were used as the gloss
adjusting agent instead of silica particles A'.
The method for preparing silica particles G will be described.
First, into a reaction vessel equipped with a stirrer, 100 g of
commercially available No. 3 sodium silicate (SiO.sub.2: 21.9 mass
%, Na.sub.2O: 7.1 mass %, SiO.sub.2/Na.sub.2O=3.19) (7 mass % as
the SiO.sub.2 concentration in the total amount of the solution)
was weighed. After addition of 100 g of water, to the solution
adjusted to 50.degree. C., 65 g of an acrylamide polymer aqueous
solution (10 mass % aqueous solution, weight average molecular
weight: 500,000) was slowly added under stirring and sufficiently
dispersed. The amount of the aqueous solution added is an amount
such that polyacrylamide anhydride reaches 30 mass % relative to
SiO.sub.2.
Subsequently, to the above-described mixed solution, 5 mass %
sulfuric acid adjusted to 50.degree. C. in advance was added, and
the pH of the mixed solution was adjusted to 10. Then, stirring was
stopped, and the mixed solution was left to stand as it was for 100
hours. Thereafter, the solution was stirred and dispersed, and the
precipitate was filtered from the mother liquid. The resulting cake
was redispersed in water. After sufficient dispersion, 5 mass %
sulfuric acid was added to the solution until the pH reached 2.0.
When the pH of the dispersion solution was substantially stabilized
at 2.0, stirring was continued for 24 hours. The dispersion
solution was filtered and washed with water, and furthermore, the
cake was repulped to be a 15 mass % spherical silica-particle
slurry.
Subsequently, the above-described slurry was filtered, and the
resulting cake was dried in a constant-temperature dryer at
110.degree. C. overnight. Thereafter, the cake was pulverized with
a sample mill to thereby obtain silica particles G Silica particles
G correspond to the aforementioned microporous particles. The
particle size distribution of silica particles G was determined
with "Multisizer 4" manufactured by Beckman Coulter Inc. using an
aperture tube having a diameter of 50 .mu.m. When the film
thickness T was 15 .mu.m, the silica particles G have an average
particle diameter R1 of 2.7 .mu.m, the standard deviation al being
1.2 .mu.m. The maximum value in the number particle size
distribution of silica particles G (the intersection of the
particle size distribution curved and the baseline) was 5.7 .mu.m,
which was thus less than 15 .mu.m (0.5T).
Coated metal sheets 38 to 40 were each produced in the same manner
as coated metal sheet 37 except that the amount of silica particles
G blended was changed as shown in Table 2. Additionally, coated
metal sheets 41 to 43 were each produced in the same manner as
coated metal sheet 38 except that the amount of acrylic particles A
blended was changed as shown in Table 2.
[Production of Coated Metal Sheets 44 to 59]
Coated metal sheet 44 was produced in the same manner as coated
metal sheet 2 except that overcoat coating material 1 to which 5
vol % of silica particles H (silica H) as the gloss adjusting agent
and 5 vol % of PAN particles B (PAN B) as the matting agent was
blended was used.
Silica particles H used were "Light Star LA-OS26BK" manufactured by
Nissan Chemical Industries, Ltd. ("Light Star" is a registered
trademark of the company.). "Light Star LA-OS26BK" corresponds to
the aforementioned microporous particles. As determined with
"Multisizer 4" manufactured by Beckman Coulter Inc. using an
aperture tube having a diameter of 50 .mu.m, silica particles H
have an average particle diameter R1 of 0.7 .mu.m, the standard
deviation .sigma.2 being 0.2 .mu.m.
PAN particles B used were "TAFTIC A-20" manufactured by Toyobo Co.,
Ltd. "TAFTIC A-20" which has been produced by a spray dry method,
corresponds to the aforementioned microporous particles. As
determined with "Multisizer 4" manufactured by Beckman Coulter Inc.
using an aperture tube having a diameter of 50 .mu.m, PAN particles
B have an average particle diameter R2 of 23 .mu.m, the standard
deviation .sigma.2 being 10.7 .mu.m.
Coated metal sheet 45 was produced in the same manner as coated
metal sheet 44 except that overcoat coating material 1 to which 0.1
vol % of silica particles A (silica A) was blended as the gloss
adjusting agent was used. Silica particles A used were the
aforementioned "NIPGEL AZ-400" manufactured by Tosoh Silica
Corporation. As determined with "Multisizer 4" manufactured by
Beckman Coulter Inc. using an aperture tube having a diameter of 50
.mu.m, silica particles A have an average particle diameter R1 of
3.3 .mu.m, the standard deviation .sigma.2 being 5.8 .mu.m.
Additionally, coated metal sheets 46 to 49 were each produced in
the same manner as coated metal sheet 45 except that the amount of
silica particles A blended was changed as shown in Tables 2 and 3.
Additionally, coated metal sheets 50 to 53 were each produced in
the same manner as coated metal sheet 47 except that the amount of
PAN particles B blended was changed as shown in Table 3.
Additionally, coated metal sheets 54 and 55 were each produced in
the same manner as coated metal sheet 47 except that the dry film
thickness T was changed as shown in Table 3. Furthermore, coated
metal sheets 56 and 57 were each produced in the same manner as
coated metal sheet 47 except that the type of the coated base sheet
was changed as shown in Table 3. Moreover, coated metal sheets 58
and 59 were each produced in the same manner as coated metal sheet
47 except that the type of the overcoat coating material was
changed as shown in Table 3.
[Production of Coated Metal Sheets 60 to 69]
Coated metal sheet 60 was produced in the same manner as coated
metal sheet 59 except that acrylic particles D (acrylic D) were
used as the matting agent instead of PAN particles B. Acrylic
particles D used were "TAFTIC AR-650M" manufactured by Toyobo Co.,
Ltd. "TAFTIC AR-650M", which has been produced by suspension
polymerization, corresponds to the aforementioned primary
particles. As determined with "Multisizer 4" manufactured by
Beckman Coulter Inc. using an aperture tube having a diameter of 50
.mu.m, acrylic particles D have an average particle diameter R2 of
30 .mu.m, the standard deviation .sigma.2 being 6.7 .mu.m.
Coated metal sheet 61 was produced in the same manner as coated
metal sheet 59 except that overcoat coating material 1 to which 5
vol % of silica particles B (silica B) was blended, instead of
silica particles A, as the gloss adjusting agent was used. Silica
particles B used were the aforementioned "Sylysia300P" manufactured
by Fuji Silysia Chemical Ltd. Silica particles B have an average
particle diameter R1 of 2.2 .mu.m, the standard deviation .sigma.1
being 0.9 .mu.m.
Additionally, coated metal sheets 62 and 63 were each produced in
the same manner as coated metal sheet 60 except that overcoat
coating material 1 to which 5 vol % of silica particles B was
blended was used and that the amount of silica particles B blended
was changed as shown in Table 3. Additionally, coated metal sheets
64 and 65 were each produced in the same manner as coated metal
sheet 60 except that overcoat coating material 1 to which 5 vol %
of silica particles B was blended was used and that the amount of
acrylic particles D blended was changed as shown in Table 3.
Additionally, coated metal sheets 66 and 67 were each produced in
the same manner as coated metal sheet 60 except that overcoat
coating material 1 to which 5 vol % of silica particles B was
blended was used and that the dry film thickness T was changed as
shown in Table 3.
Additionally, coated metal sheet 68 was produced in the same manner
as coated metal sheet 60 except that overcoat coating material 1 to
which 5 vol % of silica particles B was blended was used and that
acrylic particles C were used instead of acrylic particles D.
Acrylic particles C used were the aforementioned "TAFTIC AR-650ML"
manufactured by Toyobo Co., Ltd. As determined with "Multisizer 4"
manufactured by Beckman Coulter Inc. using an aperture tube having
a diameter of 50 .mu.m, acrylic particles C have an average
particle diameter R2 of 80 .mu.m, the standard deviation .sigma.2
being 20 .mu.m.
Additionally, coated metal sheet 69 was produced in the same manner
as coated metal sheet 68 except that overcoat coating material 1 to
which 5 vol % of silica particles B was blended was used and that
acrylic particles E (acrylic E) were used instead of acrylic
particles C. Acrylic particles E used were the aforementioned
"TAFTIC FH-S010" manufactured by Toyobo Co., Ltd. As determined
with "Multisizer 4" manufactured by Beckman Coulter Inc. using an
aperture tube having a diameter of 50 .mu.m, acrylic particles E
have an average particle diameter R2 of 10 .mu.m, the standard
deviation .sigma.2 being 6.3 .mu.m.
The type of the coated base sheet, the type and film thickness of
the overcoat coating film, the types of the gloss adjusting agent
and the matting agent, the number average particle diameter, the
standard deviation of the number particle size distribution and the
like of coated metal sheets 1 to 69 produced are shown in Tables 1
to 3. Incidentally, "'" of the type of the gloss adjusting agent
indicates that the agent has been classified.
TABLE-US-00006 TABLE 1 Gloss adjusting agent Matting agent Coated
Overcoat (R1 + (R2 + Primary particles/ base Coating T R1 .sigma.1
Content 2.sigma.1)/ R2 .sigma.2 Content 2.si- gma.2)/ Microporous
No. sheet material (.mu.m) Type (.mu.m) (.mu.m) (vol %) T Type
(.mu.m) (.mu.m) (vol %) T particles Category 1 1 1 15 Silica A' 2.5
1.0 0.2 0.3 Acrylic A 40 4.0 5 3.2 Primary particles Example 2 1 1
15 Silica A' 2.5 1.0 5 0.3 Acrylic A 40 4.0 5 3.2 Primary particles
3 1 1 15 Silica A' 2.5 1.0 10 0.3 Acrylic A 40 4.0 5 3.2 Primary
particles 4 1 1 15 Silica A' 2.5 1.0 15 0.3 Acrylic A 40 4.0 5 3.2
Primary particles 5 1 1 15 Silica A' 2.5 1.0 5 0.3 Acrylic A 40 4.0
0.2 3.2 Primary particles 6 1 1 15 Silica A' 2.5 1.0 5 0.3 Acrylic
A 40 4.0 10 3.2 Primary particles 7 1 1 15 Silica A' 2.5 1.0 5 0.3
Acrylic A 40 4.0 15 3.2 Primary particles 8 1 1 13 Silica A' 2.2
0.9 5 0.3 Acrylic A 40 4.0 5 3.7 Primary particles 9 1 1 17 Silica
A' 2.8 1.1 5 0.3 Acrylic A 40 4.0 5 2.8 Primary particles 10 1 1 20
Silica A' 3.0 1.5 5 0.3 Acrylic A 40 4.0 5 2.4 Primary particles 11
2 1 15 Silica A' 2.5 1.0 5 0.3 Acrylic A 40 4.0 5 3.2 Primary
particles 12 1 2 15 Silica A' 2.5 1.0 5 0.3 Acrylic A 40 4.0 5 3.2
Primary particles 13 1 3 15 Silica A' 2.5 1.0 5 0.3 Acrylic A 40
4.0 5 3.2 Primary particles 14 1 1 15 Silica B' 2.0 0.5 0.2 0.2
Acrylic A 40 4.0 5 3.2 Primary particles 15 1 1 15 Silica B' 2.0
0.5 5 0.2 Acrylic A 40 4.0 5 3.2 Primary particles 16 1 1 15 Silica
B' 2.0 0.5 10 0.2 Acrylic A 40 4.0 5 3.2 Primary particles 17 1 1
15 Silica B' 2.0 0.5 15 0.2 Acrylic A 40 4.0 5 3.2 Primary
particles 18 1 1 15 Silica B' 2.0 0.5 5 0.2 Acrylic A 40 4.0 0.2
3.2 Primary particles 19 1 1 15 Silica B' 2.0 0.5 5 0.2 Acrylic A
40 4.0 10 3.2 Primary particles 20 1 1 15 Silica B' 2.0 0.5 5 0.2
Acrylic A 40 4.0 15 3.2 Primary particles 21 1 1 13 Silica B' 1.9
0.4 5 0.2 Acrylic A 40 4.0 5 3.7 Primary particles 22 1 1 17 Silica
B' 2.1 0.7 5 0.2 Acrylic A 40 4.0 5 2.8 Primary particles 23 1 1 20
Silica B' 2.2 0.8 5 0.2 Acrylic A 40 4.0 5 2.4 Primary
particles
TABLE-US-00007 TABLE 2 Gloss adjusting agent Matting agent Coated
Overcoat (R1 + (R2 + Primary particles/ base Coating T R1 .sigma.1
Content 2.sigma.1)/ R2 .sigma.2 Content 2.si- gma.2)/ Microporous
No. sheet material (.mu.m) Type (.mu.m) (.mu.m) (vol %) T Type
(.mu.m) (.mu.m) (vol %) T particles Category 24 2 1 15 Silica B'
2.0 0.5 5 0.2 Acrylic A 40 4.0 5 3.2 Primary particles Example 25 1
2 15 Silica B' 2.0 0.5 5 0.2 Acrylic A 40 4.0 5 3.2 Primary
particles 26 1 3 15 Silica B' 2.0 0.5 5 0.2 Acrylic A 40 4.0 5 3.2
Primary particles 27 1 1 15 Silica C' 3.5 2.2 5 0.5 Acrylic A 40
4.0 5 3.2 Primary particles 28 1 1 15 Silica D' 3.7 2.1 5 0.5
Acrylic A 40 4.0 5 3.2 Primary particles 29 1 1 13 Silica E' 7.9
0.6 5 0.7 Acrylic A 40 4.0 5 3.7 Primary particles 30 1 1 13 Silica
F 7.5 0.8 5 0.7 Acrylic A 40 4.0 5 3.7 Primary particles 31 1 1 15
PAN A' 5.0 0.6 5 0.4 Acrylic A 40 4.0 5 3.2 Primary particles 32 1
1 15 CaCPC A' 5.0 0.5 5 0.4 Acrylic A 40 4.0 5 3.2 Primary
particles 33 1 1 15 Silica B' 2.0 0.5 5 0.2 Urethane 30 3.0 5 2.4
Primary particles 34 1 1 15 Silica B' 2.0 0.5 5 0.2 Glass 20 5.0 5
2.0 Primary particles 35 1 1 15 Silica B' 2.0 0.5 5 0.2 Acrylic B
60 5.0 5 4.7 Primary particles 36 1 1 15 Silica B' 2.0 0.5 5 0.2
Acrylic C 75 15.0 5 7.0 Primary particles 37 1 1 15 Silica G 2.7
1.2 0.2 0.3 Acrylic A 40 4.0 5 3.2 Primary particles 38 1 1 15
Silica G 2.7 1.2 5 0.3 Acrylic A 40 4.0 5 3.2 Primary particles 39
1 1 15 Silica G 2.7 1.2 10 0.3 Acrylic A 40 4.0 5 3.2 Primary
particles 40 1 1 15 Silica G 2.7 1.2 15 0.3 Acrylic A 40 4.0 5 3.2
Primary particles 41 1 1 15 Silica G 2.7 1.2 5 0.3 Acrylic A 40 4.0
1 3.2 Primary particles 42 1 1 15 Silica G 2.7 1.2 5 0.3 Acrylic A
40 4.0 10 3.2 Primary particles 43 1 1 15 Silica G 2.7 1.2 5 0.3
Acrylic A 40 4.0 15 3.2 Primary particles 44 1 1 15 Silica H 0.7
0.2 5 0.1 PAN B 23 10.7 5 3.0 Microporous Compar- particles ative
45 1 1 15 Silica A 3.3 5.8 0.1 1.0 PAN B 23 10.7 5 3.0 Microporous
Example particles 46 1 1 15 Silica A 3.3 5.8 1 1.0 PAN B 23 10.7 5
3.0 Microporous particles
TABLE-US-00008 TABLE 3 Gloss adjusting agent Matting agent Coated
Overcoat (R1 + (R2 + Primary particles/ base Coating T R1 .sigma.1
Content 2.sigma.1)/ R2 .sigma.2 Content 2.si- gma.2)/ Microporous
No. sheet material (.mu.m) Type (.mu.m) (.mu.m) (vol %) T Type
(.mu.m) (.mu.m) (vol %) T particles Category 47 1 1 15 Silica A 3.3
5.8 5 1.0 PAN B 23 10.7 5 3.0 Microporous Compar- particles ative
48 1 1 15 Silica A 3.3 5.8 13 1.0 PAN B 23 10.7 5 3.0 Microporous
Example particles 49 1 1 15 Silica A 3.3 5.8 20 1.0 PAN B 23 10.7 5
3.0 Microporous particles 50 1 1 15 Silica A 3.3 5.8 5 1.0 PAN B 23
10.7 0.1 3.0 Microporous particles 51 1 1 15 Silica A 3.3 5.8 5 1.0
PAN B 23 10.7 1 3.0 Microporous particles 52 1 1 15 Silica A 3.3
5.8 5 1.0 PAN B 23 10.7 13 3.0 Microporous particles 53 1 1 15
Silica A 3.3 5.8 5 1.0 PAN B 23 10.7 20 3.0 Microporous particles
54 1 1 8 Silica A 3.3 5.8 5 1.9 PAN B 23 10.7 5 5.6 Microporous
particles 55 1 1 22 Silica A 3.3 5.8 5 0.7 PAN B 23 10.7 5 2.0
Microporous particles 56 3 1 15 Silica A 3.3 5.8 5 1.0 PAN B 23
10.7 5 3.0 Microporous Reference particles Example 57 2 1 15 Silica
A 3.3 5.8 5 1.0 PAN B 23 10.7 5 3.0 Microporous Compar- particles
ative 58 1 2 15 Silica A 3.3 5.8 5 1.0 PAN B 23 10.7 5 3.0
Microporous Example particles 59 1 3 15 Silica A 3.3 5.8 5 1.0 PAN
B 23 10.7 5 3.0 Microporous particles 60 1 3 15 Silica A 3.3 5.8 5
1.0 Acrylic D 30 6.7 5 2.9 Primary particles 61 1 1 15 Silica B 2.2
0.9 5 0.3 PAN B 23 10.7 5 3.0 Microporous particles 62 1 1 15
Silica B 2.2 0.9 0.1 0.3 Acrylic D 30 6.7 5 2.9 Primary particles
63 1 1 15 Silica B 2.2 0.9 20 0.3 Acrylic D 30 6.7 5 2.9 Primary
particles 64 1 1 15 Silica B 2.2 0.9 5 0.3 Acrylic D 30 6.7 0.1 2.9
Primary particles 65 1 1 15 Silica B 2.2 0.9 5 0.3 Acrylic D 30 6.7
20 2.9 Primary particles 66 1 1 8 Silica B 2.2 0.9 5 0.5 Acrylic D
30 6.7 5 5.4 Primary particles 67 1 1 22 Silica B 2.2 0.9 5 0.2
Acrylic D 30 6.7 5 2.0 Primary particles 68 1 1 15 Silica B 2.2 0.9
5 0.3 Acrylic C 80 20 5 8.0 Primary particles 69 1 1 15 Silica B
2.2 0.9 5 0.3 Acrylic E 10 6.3 5 1.5 Primary particles
[Evaluation]
Coated metal sheets 1 to 69 were each subjected to the measurement
and test described below.
(1) Glossiness at 75 Degrees
Glossiness at 75 degrees (G75), specified by JIS Z8741, of each of
coated metal sheets 1 to 69 was measured with Gloss meter VG-2000
manufactured by NIPPON DENSHOKU INDUSTRIES CO., LTD.
(2) Coating Appearance
The appearance of the coating film of each of coated metal sheets 1
to 69 after drying was evaluated in accordance with the following
criteria.
(Evaluation Criteria)
Y1: No abnormal gloss and coating film defects are observed, and a
satisfactory appearance is observed.
Y2: Any of abnormalities D1 to D3 shown below is observed.
D1: Gloss is extremely high (glossiness is higher than 25)
D2: Foaming is observed
D3: Streaks are observed
(3) Scratch Resistance
Clemens-type scratch test was conducted by using a diamond needle
having a diameter of 125 .mu.m and applying a load of 400 g, and
evaluation was made in accordance with the following criteria.
(Evaluation Criteria)
N: No scratch reaching the base material (metal sheet) is
observed
Y: Scratches reaching the base material (metal sheet) are
observed
(4) Processed-Part Adhesiveness
Coated metal sheets 1 to 69 were each subjected to 0T bending
(adhesion bending), and the 0T bended portion was subjected to
cellophane tape-peeling test and evaluated in accordance with the
following criteria.
(Evaluation Criteria)
N: Peeling of the coating film is not observed
Y: Peeling of the coating film is observed
(5) Flat Portion-Corrosion Resistance
First, coated metal sheets 1 to 69 were each subjected to the xenon
lamp method-accelerated weathering test specified by JIS K5600-7-7
(ISO11341: 2004) for 1,000 hours. Then, each sheet was subjected to
the "neutral salt water spray cycle test" specified by JIS H8502
(so-called JASO method) for 720 hours. The above-described two
tests were conducted as one cycle. Test products subjected to one
cycle (corresponding to about five-year service life in actual use)
and test products subjected to two cycles (corresponding to about
10-year service life) each for coated metal sheets 1 to 69 were
washed with water. After observed for the presence or absence of
coating film blistering at the flat portion of the coated metal
sheet by visual observation and magnified observation with a loupe
having a magnification of 10, the sheets were evaluated in
accordance with the following criteria.
(Evaluation Criteria)
N: No blistering is observed
Y1: Slightly subtle blistering is observed by magnified
observation, but no blistering is visually observed
Y2: Blistering is visually observed
The evaluation results of coated metal sheets 1 to 69 are shown in
Tables 4 to 6.
TABLE-US-00009 TABLE 4 Flat portion Coating Scratch Processed-
corrosion appear- resis- part adhe- 1 2 No. G75 ance tance siveness
cycle cycles Category 1 24 Y1 Y1 Y1 N N Example 2 18 Y1 Y1 Y1 N N 3
5 Y1 Y1 Y1 N N 4 3 Y1 Y1 Y1 N N 5 25 Y1 Y1 Y1 N N 6 10 Y1 Y1 Y1 N N
7 7 Y1 Y1 Y1 N N 8 15 Y1 Y1 Y1 N N 9 19 Y1 Y1 Y1 N N 10 21 Y1 Y1 Y1
N N 11 17 Y1 Y1 Y1 N N 12 18 Y1 Y1 Y1 N N 13 18 Y1 Y1 Y1 N N 14 25
Y1 Y1 Y1 N N 15 17 Y1 Y1 Y1 N N 16 4 Y1 Y1 Y1 N N 17 2 Y1 Y1 Y1 N N
18 25 Y1 Y1 Y1 N N 19 10 Y1 Y1 Y1 N N 20 6 Y1 Y1 Y1 N N 21 16 Y1 Y1
Y1 N N 22 18 Y1 Y1 Y1 N N 23 19 Y1 Y1 Y1 N N
TABLE-US-00010 TABLE 5 Flat portion corrosion Coating Scratch
Processed- resistance appear- resis- part adhe- 1 2 No. G75 ance
tance siveness cycle cycles Category 24 17 Y1 Y1 Y1 N N Example 25
16 Y1 Y1 Y1 N N 26 17 Y1 Y1 Y1 N N 27 16 Y1 Y1 Y1 N N 28 17 Y1 Y1
Y1 N N 29 15 Y1 Y1 Y1 N Y1 30 15 Y1 Y1 Y1 N Y1 31 12 Y1 Y1 Y1 N N
32 12 Y1 Y1 Y1 N N 33 19 Y1 Y1 Y1 N N 34 23 Y1 Y1 Y1 N N 35 4 Y1 Y1
Y1 N N 36 3 Y1 Y1 Y1 N N 37 25 Y1 Y1 Y1 N N 38 17 Y1 Y1 Y1 N N 39 5
Y1 Y1 Y1 N N 40 4 Y1 Y1 Y1 N N 41 24 Y1 Y1 Y1 N N 42 9 Y1 Y1 Y1 N N
43 7 Y1 Y1 Y1 N N 44 29 Y2 D1 Y1 Y1 -- -- Compar- 45 28 Y2 D1 Y1 Y1
-- -- ative 46 22 Y1 Y1 Y1 Y2 Y2 Example
TABLE-US-00011 TABLE 6 Flat portion corrosion Coating Scratch
Processed- resistance appear- resis- part adhe- 1 2 No. G75 ance
tance siveness cycle cycles Category 47 19 Y1 Y1 Y1 Y2 Y2 Compar-
48 5 Y1 Y1 Y1 Y2 Y2 ative 49 2 Y1 Y1 Y2 -- -- Example 50 49 Y2 D1
Y2 Y1 -- -- 51 25 Y1 Y1 Y1 Y2 Y2 52 7 Y1 Y1 Y1 Y2 Y2 53 1 Y1 Y1 Y2
-- -- 54 16 Y1 Y2 Y1 -- -- 55 -- Y2 D2 Y1 Y1 -- -- 56 19 Y1 Y1 Y1 N
Y1 Reference Example 57 19 Y1 Y1 Y1 Y2 Y2 Compar- 58 18 Y1 Y1 Y1 Y2
Y2 ative 59 19 Y1 Y1 Y1 Y2 Y2 Example 60 17 Y1 Y1 Y1 Y2 Y2 61 21 Y1
Y1 Y1 Y2 Y2 62 29 Y2 D1 Y1 Y1 -- -- 63 5 Y1 Y1 Y2 -- -- 64 51 Y2 D1
Y2 Y1 -- -- 65 3 Y1 Y1 Y2 -- -- 66 14 Y1 Y2 Y1 -- -- 67 -- Y2 D2 Y1
Y1 -- -- 68 -- Y2 D3 Y1 Y1 -- -- 69 32 Y2 D1 Y2 Y1 -- --
As clear from Tables 2, 3, 5, and 6 coated metal sheet 44 in which
the gloss adjusting agent had a number average particle diameter R1
less than 2 .mu.m and coated metal sheets 45 and 62 in which the
content of the gloss adjusting agent in the overcoat coating film
was less than 0.2 vol % did not achieve the intended glossiness and
had an inferior coating appearance. Additionally, coated metal
sheets 50 and 64 having a matting agent-content less than 0.2 vol %
and coated metal sheet 69 having (R2+2.sigma.2)/T less than 2.0 did
not achieve the intended gloss and had an inferior coating
appearance and inferior scratch resistance. Furthermore, coated
metal sheet 68 having (R2+2.sigma.2)/T more than 7.0 had the
occurrence of streaks and had an inferior coating appearance.
Coated metal sheets 54 and 66 in which the overcoat coating film
had a film thickness less than 13 .mu.m had inferior scratch
resistance. Meanwhile, coated metal sheets 55 and 67 in which the
overcoat coating film had a film thickness more than 20 .mu.m had
the occurrence of foaming and an inferior coating appearance.
Coated metal sheets 49 and 63 in which the content of the gloss
adjusting agent in the overcoat coating film was more than 15 vol %
and coated metal sheets 53 and 65 in which the content of the
matting agent in the overcoat coating film was more than 15 vol %
had inferior processed-part adhesiveness.
Coated metal sheet 60 having (R1+2.sigma.1)/T more than 0.7, coated
metal sheet 61 in which microporous particles were used as the
matting agent, or coated metal sheets 46 to 48, 51, 52, 57 to 59
satisfying both of these were not able to achieve even flat
portion-corrosion resistance, which corresponds to five years of
actual use.
In contrast, as clearly from Tables 1, 2, 4, and 5, coated metal
sheets 1 to 43 in which the gloss adjusting agent had a number
average particle diameter R1 of 2 .mu.m or more and
(R1+2.sigma.1)/T of 0.7 or less, the matting agent was primary
particles and had (R2+2.sigma.2)/T of 2.0 or more and 7.0 or less,
and the overcoat coating film had a film thickness T of 13 .mu.m or
more and 20 .mu.m or less achieved the intended glossiness and were
excellent in any of the coating appearance, scratch resistance,
processed-part adhesiveness, and flat portion-corrosion resistance.
Particularly, the flat portion-corrosion resistance of the coated
metal sheets 1 to 43 was, apparent from the comparison with coated
metal sheet 56, equivalent to or greater than the flat
portion-corrosion resistance of a coated metal sheet subjected to
chromate-containing chemical conversion and containing chromium as
the anti-rust pigment.
This application claims the priority of Japanese Patent Application
No. 2014-59950 filed on Mar. 24, 2014, the entire contents of which
including the specification and drawings are incorporated herein by
reference.
INDUSTRIAL APPLICABILITY
In the coated metal sheet according to the present invention,
reduction in the corrosion resistance in the flat portion,
attributable to collapse and fall-off of the gloss adjusting agent
and the matting agent from the overcoat coating film, is prevented.
Thus, a coated metal sheet that exhibits the intended appearance
and corrosion resistance for a long period can be obtained, even if
used in an exterior application for a long period. Accordingly, the
present invention is expected to further prolong the life of coated
metal sheets for exterior use and to further enhance their
usage.
* * * * *
References